Continue game play:
Hold A + B + Select and press Start at the game over screen.

Thirty lives:
Press Up(2), Down(2), Left, Right, Left, Right, A, B, Select, Start while the title screen is scrolling down after the NES is powered on. Note: For a two player game, press Up(2), Down(2), Left, Right, Left, Right, A, B, Select(2), Start

Hint: Easy Boss kills:
Begin game play in single player mode. Summon a CPU assistant and move to a safe location. Repeat this procedure until the Boss is defeated.

Hint: Survive falls:
If your character falls into a pit, immediately press Start to pause game play. Hold A and press Start to jump out of the pit and save a life. This can also be used as a super-jump to reach high places in other parts of the game.